Non-volatile memory devices based on the resistivity switching of transition-metal oxide materials has become a major focus for developing the next generation universal RAM devices. As may be appreciated, non-volatile memory does not require a constant power supply to retain stored information in contrast to volatile memory, which does require a constant power supply to retain stored information. Thus, non-volatile memory may have advantages for long term storage of critical data.
Many types of materials have been utilized to create non-volatile memory elements. Nickel oxide thin films are one such material. Conventionally, nickel oxide thin films have been prepared through physical-vapor deposition (PVD) methods by reactive sputtering of Ni targets in an O2 enriched environment. In addition, in some examples, conventional methods have generated reproducible resistance switching in an appropriate metal-insulator (NiO thin film)-metal structure with superior performances both in terms of reliability and speed.
Research of nickel oxide thin films has demonstrated that the defect chemistry of those films can play a role in determining the switching performance of the associated memory devices derived from those films. For example, according to some research, the atomic elemental ratio between nickel and oxygen must be carefully controlled to within certain ranges to obtain a desired resistance switching. Current deposition techniques may not provide sufficiently precise control over chemical defects in oxide materials.
As such, methods for forming nickel oxide films for use with resistive switching memory devices are presented herein.